The 337th Aeronautical Systems Group is an inactive United States Air Force unit. Its last assignment was with the Aeronautical Systems Center of Air Force Materiel Command at Wright Patterson Air Force Base, Ohio, where it was inactivated in 2008.

The group was first activated in 1942 at Morris Field, North Carolina as the 337th Fighter Group. During World War II it acted as a Replacement Training Unit for fighter pilots. The group was disbanded in 1944 in a major reorganization of Army Air Forces training units.

The 337th was activated again in 1955, when it replaced the 503d Air Defense Group at Portland International Airport as part of Air Defense Command (ADC)'s Project Arrow, which was designed to revive fighter units that had served during World War II and replace ADC's post-war units. It provided air defense for the Pacific northwest until it was inactivated in 1966, earning two Air Force Outstanding Unit Awards. The commander at Portland had been Lt. Col. George W. White, who had previously been with the 503d Air Defense Group, and who died during his command at 43 years of age, in August 1957.

In January 2005 the Training Aircraft Systems Group was activated as part of the Air Force Materiel Command Transformation, which replaced traditional procurement offices with wings, groups and squadrons. In May 2006 the two groups were consolidated and the consolidated unit named the 337th Aeronautical Systems Group. In 2008, the unit was inactivated and its squadrons reassigned to the 877th Aeronautical Systems Group.

The 337th Fighter Group was activated in July 1942 at Morris Field, North Carolina with the 98th, 303d, and 304th Fighter Squadrons assigned. It received its initial cadre from the 20th Fighter Group. However, two of its squadrons departed Morris Field the day they were activated, with the 303d moving to Spartanburg Army Air Field and the 304th to the Myrtle Beach Bombing Range, both in South Carolina, to be organized. The group's initial equipment was a mix of obsolescent fighter aircraft. Although these were mostly Curtiss P-40 Warhawks, the 304th Squadron also flew Bell P-39 Airacobras and Republic P-43 Lancers.

Two weeks later, the group and the 98th Squadron moved to Drew Field, near Tampa, Florida. The 303d Squadron joined them later that month, while the 304th moved to the Tampa Bay Area, but to Pinellas Army Air Field, on the other side of the bay. The group operated as a Replacement Training Unit (RTU), with the Warhawk. RTUs were oversized units which trained individual pilots or aircrews.

In January 1943 the group and the squadrons at Drew Field moved to Sarasota Army Air Field, where the following month the group added a fourth squadron, the 440th Fighter Squadron. In August, the 440th joined the 304th at Pinellas and the group maintained a split operation at Sarasota and Pinellas until it was disbanded. The group transitioned to North American P-51 Mustangs in early 1944.

However, the Army Air Forces (AAF) was finding that standard military units, which were based on relatively inflexible tables of organization were not proving to be well adapted to the training mission. Accordingly, it adopted a more functional system in which each base was organized into a separate numbered unit. The group and its squadrons were disbanded in May 1944. The 336th AAF Base Unit (Replacement Training Unit, Fighter) assumed the mission of the group at Sarasota, while the 341st AAF Base Unit (Replacement Training Unit, Fighter) took over the group's equipment at Pinellas.